Telephone and telegraph system with amplifiers



April '14, 1925. I 1,533,842

H. FASSBENDER ET AL TELEPHONE AND TELEGRAPH SYSTEM WITH AM PLIFIERS I Filed May 3, 1921 Patented Apr. 14, 192 5.

PATENT OFFICE.

HEINRICH FASSBENIDEB, or CHABLOITENBURG. AND ERICK HABANN, OF BERLIN,

ERMANY, As'sIGNoRs GERMANY.

T0 nnti'r'scr'tiz TELEPHONWERKE, G. M. B. 11., 0F BERLIN,

TELEPHONE Ann ThtEGRAPH SYSTEM Wren AMPLIFIERS.

Application filed may a, 1921. Serial No. 466,525.

To critic/10m it may covwem: p p i Be it known that we, Hizismrcir FASSRFY- man and E ii'o 'r H.-\iii-\l\ :j, both German-cit 'zens, and residing git Charlottenbilrg, Germanig and Berlin, Germany, have invented certain ne uand useful I11'1pro\'e i ients Relz'itii'ig to'lTelephoiie emu Telegraph Systems with Ani'plitiers (for wliich we have filed aplications in Germany dated, resn'ecti "ely, 27th August, 1918, and 10th March 1920* and in England dated 8th Marc-1n 1921), of which the following is a specific-inn. o For communication over telegraph zijnd telephone lines 'aiiiplifiei's are used ofwhich the principal portion isa 'dischai'getiibe and in View of the uni-directional action of these amplifiers it isn'ec'ess'ziry to provide for the iransn'iissioh of message two amplifiers be tween two points one of the niii'plitiers serving for the n'iessage passing in one direction and the other in the opposite direction. F or this purpose hitl'ie'rto either two parallel lines have been so arranged that em-h was only i'iscd with it's amplifier for message in one direction, or only one line was used of whielr the amplifier was reversed from one amplifying direction to the oth r which is eii'ected either in accordance with the direction of the messages, or independently of thedirection continuouslyfat very short inter 'vals. Both methods are expensive and 1h- COHVCIlllll] in use.

The'subject of the ifiiy'ention is a methtfidv accordingto which only one conductor and two uni-dire'ctioii'al amplifiers such as ther- Inionic tubes of known type are provided, the amplifiers being brought in correct operation without any necessity for reversing. The two thermionic tubes are arranged permanently in parallel line branches and the transmission of the message currents is efhated by means ofhigh frequency carrier waves. The separation of the two branches which is necessary in order to avoid howling of the amplifiers, is effected by tuning each of the said branches to a different high frequency oscillation whereby each permits only of communication in one direction namely that which is eifected at the same frequency oscillation as that of the branch through which it is to pass so that the speaking current in each direction of s eaking automatically finds its correct pat through the corresponding amplifier.

In the drawings Figuresl and 2 show dia gr'alinnzitie' arrangements according to the first Ihethod. v p a I a In Figure 1 of the drawing there is in; s'erted between the incoming lin'eL the outgoing line L by means of four transformers T T T T a 'pz'iirofyalvjes R- Bf serving as co 'ipling members, the yalve R having its rid circuit connected to the line L, orto the transfoinier '11 by an oscillating circuit S which consists in the known manner of an i'nd ction coil and a tuning condenser. The 'zn'i'od'e' circuit of this valve is enn teu directly to the transformer T or the line L; The vuli'e R is connected in the rem-SQ mum. The anodes of the y'zilves 'are ink ed by A the grids by G and the glowing c them s by K. Each of the two valve branches is tuned to a particular high frequency by theoscillating circuits so that it does not allow the other to pass therethrongl'i. The current coming from p the right for example follows the path, indicated bytlie arrow, only through the ampliiying'ialvelig, the current coining from the i left howeveigonly passes through the amplifyingyalve R I In Figure 2 practically the same arrangement is illustri ted withthe difference that the tuning oscillating circuits S S are not i on the local circuits of the valves but are connected to the distant lines and the trans-- formers T T and T T are connected in parallel with these instead of in series as shown in Figure 1, This causes no difference in operation according to the invention.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is 1. A high frequency communication line arrangement, comprising an incoming and an outgoing line, two branches in parallel connecting both said lines together, two amplifying thermionic tubes arranged one in each branch, the said tubes being so arranged that the grid or one tube and the anode of another tube are electrically joined to the same line, and tuning means whereby each of the said branches is tuned to another high frequency oscillation and so that communication can be effected in one direction only and this at the particular frequency to which the tube appertaining to this direction is tuned, said tuning also preventing howling.

2. A telegraph or telephone line arrangement for high frequency transmission comprising an incomlng and an outgoing line, two branches in parallel connecting both said lines together, four transformers having one coil connected to one line;- two amplifiers arranged one in each line branch, the amplifiers being so arranged that the anode circuit of one amplifier and the grid circuit of the second amplifier are connected to transformer coils on the incoming line, whilst the grid circuit of the first amplifier and the anode circuit of the second amplifier are connected to transformer coils on the outgoing line, and tuning means for each of said amplifiers, said tuning means being such that each amplifier is tuned to a difi'erent high frequency whereby communication can only be eifected through each amplifier in one direction and at the articular high frequency to which the particular amplifier is tuned.

HEINRICH FASSBENDER. ERICH HABANN. 

